After some research I've finally learned that the function's parameter is a bitmask, and one have to combine several values to get the desired result. The final combination is not overly logical, but it works as intended, throwing an exception on a query error while ignoring warnings.
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
will produce the desired result:
Fatal error: Uncaught exception 'mysqli_sql_exception' with message 'You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'foo' at line 1'
